6,221 research outputs found

    Development, design, fabrication and evaluation of a real-time video compression system

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    This is the final report on the work done by David Hein at the NASA-AMES Research Center. The main emphasis is on the work done on the Conditional Replenishment Emulator. The progress for May and a description of the emulator are given. Brief summaries of the work that was done in the other areas covered by the contract over the entire contract period are also provided

    A primal-dual formulation for certifiable computations in Schubert calculus

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    Formulating a Schubert problem as the solutions to a system of equations in either Pl\"ucker space or in the local coordinates of a Schubert cell typically involves more equations than variables. We present a novel primal-dual formulation of any Schubert problem on a Grassmannian or flag manifold as a system of bilinear equations with the same number of equations as variables. This formulation enables numerical computations in the Schubert calculus to be certified using algorithms based on Smale's \alpha-theory.Comment: 21 page

    Generating Interpretable Fuzzy Controllers using Particle Swarm Optimization and Genetic Programming

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    Autonomously training interpretable control strategies, called policies, using pre-existing plant trajectory data is of great interest in industrial applications. Fuzzy controllers have been used in industry for decades as interpretable and efficient system controllers. In this study, we introduce a fuzzy genetic programming (GP) approach called fuzzy GP reinforcement learning (FGPRL) that can select the relevant state features, determine the size of the required fuzzy rule set, and automatically adjust all the controller parameters simultaneously. Each GP individual's fitness is computed using model-based batch reinforcement learning (RL), which first trains a model using available system samples and subsequently performs Monte Carlo rollouts to predict each policy candidate's performance. We compare FGPRL to an extended version of a related method called fuzzy particle swarm reinforcement learning (FPSRL), which uses swarm intelligence to tune the fuzzy policy parameters. Experiments using an industrial benchmark show that FGPRL is able to autonomously learn interpretable fuzzy policies with high control performance.Comment: Accepted at Genetic and Evolutionary Computation Conference 2018 (GECCO '18

    Reserve requirements: A modern perspective

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    The discussion in many money and banking textbooks would suggest that the Federal Reserve requires depository institutions to hold a minimum level of non-interest-earning reserves because (1) reserve requirements are a monetary policy tool that allows the Fed to expand the money supply and lower interest rates, and (2) reserve requirements improve the safety and soundness of depository institutions. This article argues that this "conventional wisdom" view is too narrow. ; The Fed often uses reserve requirement changes, the authors contend, to achieve non-monetary-policy objectives, as it did in 1992 to improve the profitability of depository institutions and ease the credit crunch of that time. The authors also challenge the notion that higher reserve requirements necessarily lead to greater safety and lower default risk for depository institutions. ; The article examines the relationship between reserve requirement changes and monetary policy, with the aim of demonstrating the recent, limited usefulness of reserve requirements as a monetary policy tool. The article proposes a more modern view of reserve requirements as a tax on depository institutions, ponders who really bears this tax, and summarizes a large and growing literature suggesting that perceived bank profitability is inversely affected by announced changes in reserve requirement ratios. The article also provides new evidence that the 1992 reserve requirement reductions were not associated with an increase in default risk for financial institutions that issue reservable instruments, as the conventional view would suggest.Monetary policy ; Financial institutions ; Bank reserves

    A Town Girl Becomes a Farm Helper

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    Compendium of Applications Technology Satellite user experiments

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    The achievements of the user experiments performed with ATS satellites from 1967 to 1973 are summarized. Included are fixed and mobile point to point communications experiments involving voice, teletype and facsimile transmissions. Particular emphasis is given to the Alaska and Hawaii satellite communications experiments. The use of the ATS satellites for ranging and position fixing of ships and aircraft is also covered. The structure and operating characteristics of the various ATS satellite are briefly described

    Graphical calculus for Gaussian pure states

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    We provide a unified graphical calculus for all Gaussian pure states, including graph transformation rules for all local and semi-local Gaussian unitary operations, as well as local quadrature measurements. We then use this graphical calculus to analyze continuous-variable (CV) cluster states, the essential resource for one-way quantum computing with CV systems. Current graphical approaches to CV cluster states are only valid in the unphysical limit of infinite squeezing, and the associated graph transformation rules only apply when the initial and final states are of this form. Our formalism applies to all Gaussian pure states and subsumes these rules in a natural way. In addition, the term "CV graph state" currently has several inequivalent definitions in use. Using this formalism we provide a single unifying definition that encompasses all of them. We provide many examples of how the formalism may be used in the context of CV cluster states: defining the "closest" CV cluster state to a given Gaussian pure state and quantifying the error in the approximation due to finite squeezing; analyzing the optimality of certain methods of generating CV cluster states; drawing connections between this new graphical formalism and bosonic Hamiltonians with Gaussian ground states, including those useful for CV one-way quantum computing; and deriving a graphical measure of bipartite entanglement for certain classes of CV cluster states. We mention other possible applications of this formalism and conclude with a brief note on fault tolerance in CV one-way quantum computing.Comment: (v3) shortened title, very minor corrections (v2) minor corrections, reference added, new figures for CZ gate and beamsplitter graph rules; (v1) 25 pages, 11 figures (made with TikZ

    Bipartite all-versus-nothing proofs of Bell's theorem with single-qubit measurements

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    If we distribute n qubits between two parties, which quantum pure states and distributions of qubits would allow all-versus-nothing (or Greenberger-Horne-Zeilinger-like) proofs of Bell's theorem using only single-qubit measurements? We show a necessary and sufficient condition for the existence of these proofs for any number of qubits, and provide all distinct proofs up to n=7 qubits. Remarkably, there is only one distribution of a state of n=4 qubits, and six distributions, each for a different state of n=6 qubits, which allow these proofs.Comment: REVTeX4, 4 pages, 2 figure
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